1. Field of the Invention
The present invention relates to the utilization of handwriting recognition (HWR) techniques in electronic devices, and particularly relates to methods of and apparatuses for inputting characters into handheld devices, handheld devices with such apparatuses, and storage media encoded with machine-readable computer program codes for implementing such methods.
2. Description of the Related Art
Nowadays, more and more electronic devices have been developed and used in people's daily lives. These electronic devices, for example, include personal computers (PC), personal digital assistants (PDA), mobile phones, electronic dictionaries, receipt printers, etc. Based on the portability and other considerations, electronic devices may be classified into handheld devices and non-handheld devices. For some electronic devices, and especially for the handheld devices, the ability of receiving and processing text information is important.
In order to input text information or characters into electronic devices, various mechanisms have been invented. Handwriting recognition is a mature technology by which ideographic characters, digits, Latin alphabets, special characters or other text may be recognized from the user's handwriting.
In early days, different kinds of characters, such ideographic characters, digits, Latin alphabets, and special characters had to be recognized in the same recognition mode. Without considering the peculiarities of different kinds of characters, these early handwriting recognition technologies cannot recognize characters accurately. Since then, technicians have been struggling to improve the accuracy of handwriting recognition technology.
At present, handwriting recognition systems operate in different recognition modes for recognizing different kinds of characters. For example, these recognition modes may include ideographic character mode (such as simplified Chinese character mode, traditional Chinese character mode, Japanese character mode, and so on), digit mode, Latin alphabet mode, special character mode, etc. But in all prior handwriting systems, before a user can write characters on the graphic writing pad, the user has to first designate an active recognition mode. Only in the active recognition mode, can the handwriting recognition system recognize what is being written on the graphic writing pad. In other words, no matter what character the user writes on the graphic writing pad, the handwriting recognition system always recognizes the handwriting as characters particularly corresponding to the active recognition mode. For example, if the active recognition mode is Chinese character mode, the handwriting recognition system recognizes whatever is written on the graphic writing pad as Chinese characters. The handwriting recognition systems operating in different recognition modes for recognizing different kinds of characters are referred to as mode-based handwriting recognition systems hereinafter.
The mode-based handwriting recognition systems have several drawbacks. The requirement of first designating a corresponding recognition mode before actually writing is very different from the natural process of writing on paper. In the case of writing contents which include different kinds of characters, a user usually mainly concentrates too much on the contents and forgets to switch the handwriting recognition modes for different kinds of characters. The need to stop while writing, find a correct recognition mode, switch to it and write previous contents once again greatly hinders the natural process of thinking and writing.
Even worse, sometimes it is not clear to the user which recognition mode is correct for some characters. For example, the inventor has noticed that in the usability test users were sometimes confused about whether punctuation marks such as comma and full stop are available in Chinese character mode or special character mode. Judging the correct recognition mode is also a burden for users using mode-based handwriting recognition systems.
To reduce users' burden of judging and switching the handwriting recognition modes, some handwriting recognition engines may work in a mixed-mode, in which the handwriting recognition engines try to find the best matches to the users' writing in all other modes, so that the users do not have to manually switch the mode. However, the intelligence of such engines is so limited that the accuracy of handwriting recognition is rather low. Also, the candidate list is messy, which makes it difficult for users to select a desired character. This is due to the fact that characters from different modes are mixed together while being displayed, and that some candidate characters for a given writing resemble very much. For example, Chinese character “one” and a dash (a straight horizontal line) are similar. So are English letter “1” and digit “1”.